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By G. J. Arseneau

ABSTRACT Mineral resource statements are reported as tonnage (volume × density) and grades. Effort is expended to accurately estimate the volume and grade, but accurately determining bulk density is often overlooked. Oversimplification of density modelling can result in potentially serious errors in tonnage estimates and over- or underestimation of metal content. A reliable bulk density model requires an adequate database and a good understanding of density variability, along with grade and geology. In this paper, the author summarizes density measuring techniques, draws on examples of simple and complex grade-variable density domains, and discusses improved approaches for minimizing density estimation errors.

Jan 1, 2014

By Y. Bai, J. J. Liu, D. Q. Li, S. Z. Liu, X. T. Wang

"This paper presents the results of an industrial test using 8 t/d of Baotou concentrate (50% REO) of a clean metallurgical process, which includes: 1. Roasting with H2SO4 at low temperature (220~260 0C) in a batch roasting furnace followed by water leaching to obtain a leach liquor as feed with a yield of >95% RE and Th, recovering F as fluoride, producing a leach residue amounting to 1/3 of an equivalent high temperature residue and containing <0.03% Th and radioactivity < 3×104 Bq/kg compared to the normal high temperature residue containing 0.2-0.3% Th and 1×105 Bq/kg. 2. Separating Th with N1923 and extracting RE by P507 has been completed in mixer-settlers. Test results indicate that the ThO2 product has a purity of > 95% with a yield of 99%, and the RE has a yield of >95%, in which ThO2/REO <5×10-6, and that P507 loaded RE connect straight with separating RE using P507-HCl system. 3. Treatment and multipurpose use of "three wastes" (water, gas and solids) are discussed in some detail."

Jan 1, 2014

By Bengt H. Fellenius

"ABSTRACTAn example from a guidelines document for the Eurocode is discussed that addresses design for geotechnical strength of piled foundations in settling soil, generating drag force and downdrag. A modified example of geotechnical response is then analyzed in a failure mode, Ultimate Limit States (ULS), and stationary long-term state, Serviceable Limit States (SLS). It is shown that the Eurocode principles, when applied to correctly determined forces, results in an irrational and costly design. The results of the analysis of the modified example are applied to eight different codes pertaining to piled foundations from USA, Canada, Europe, and other countries. Several of the codes require that the drag force be included as a load in a ULS design, which an absurd and costly requirement, in some codes, in one case made even worse by combining drag force with live load. A major weakness of almost all codes is their minimal treatment and sometimes total absence of aspects of settlement of piled foundation. In contrast, my main argument is that design for capacity, whether in working stress approach, or by LFRD or ULS approaches, is not always safe unless a thorough settlement analysis shows that the design also meets the requirements of the SLS.1. INTRODUCTIONFirst, there were analysis, design, and construction establishing a State-of-Practice, SOP. Then, came codes and specifications summarizing the SOP, as interpreted by a committee. When the state-of-art, SOA, was not understood by that SOP-interpreting committee, the codes and specifications are uneconomical and, sometimes, also unsafe.The paper first presents an example quoted from two commentaries on the Eurocode 7 on design for geotechnical strength by the Eurocode (1997). The example is then modified to a more realistic case and analyzed in failure mode (ultimate limit states, ULS) and in the context of settlement (serviceability limit states, SLS). The analysis results are then applied to eight codes addressing piled foundation design and changes necessary for the referenced codes and specifications to be closer to the SOA are identified."

Jan 1, 2014

By D. Thibault, A. Akhiate, M. Brochu, E. Braud

Cast martensitic stainless steels, 13%Cr-4%Ni, having carbon contents between 0.018 wt% and 0.067 wt% were normalized, air quenched, and tempered at two different temperatures (550°C and 610°C). Their microstructures were characterized by optical microscopy and X-ray diffraction (XRD). Macro and microhardness, tensile strengths, and impact resistance were quantified for each material and condition. Results show that the prior-austenite grain size is constant through the materials but the percentage of reformed austenite, contained in the martensitic matrix, depends strongly on the material chemistry and on the tempering temperature and on its duration. It is observed that, independently of tempering conditions, an increase in carbon content increases the material hardness and tensile strengths, whereas the elongation remains constant. In contrast, the results of Charpy type impact toughness tests show a different trend. The material containing the average carbon content (0.034 wt%) is significantly tougher than the two other alloys. Surprisingly, the toughness of the steel containing 0.034 wt% carbon was found independent of the reformed austenite content. It is thus concluded that carbon and reformed austenite contents are not the only parameters affecting the toughness of these steels.

Jan 1, 2014

By Johnny Lyons-Baral, John Kemeny, Don Kraemer

Ground vibrations from blasting can result in the degradation and failure of rock and soil exposures, as well as damaging neighboring houses and buildings. At the same time, vibration provides an opportunity to regularly monitor the rock and soil exposures. If a geophone or accelerometer is attached to a rock block or wedge on a mine slope, for example, then blast vibrations will regularly “sound” the rock block and the resulting vibrations can be used to assess the stability of the rock mass in the neighborhood of the accelerometer, as well as monitoring the properties of the blast. This paper describes the development of a wireless sensor network based on inexpensive MEMS accelerometers for blast monitoring and rock and soil structural health monitoring. The wireless sensors are placed at various locations in and around an open pit mine or quarry, and transmit data to a central source after ground vibration events occur. As described in the paper, a variety of wireless and non-wireless accelerometers were tested in actual field conditions. This includes the monitoring of over 30 blasts at an open pit mine in Arizona with as many as nine simultaneous accelerometers. Matlab was used to process all the data and develop innovative methods to view and interpret the data. This includes the use of the wavelet transform to determine resonance frequencies, and the use of both ground resonance frequencies and scaled-distance peak particle velocity (ppv) relationships to assess slope stability. As part of this research, a three-dimensional point cloud environment for viewing and analyzing the vibration data from the sensors has also been developed.

Jan 1, 2014

By P. I. James, M. R. Baker

Este artículo analiza la nueva producción de cobre a partir de "minerales de desecho" de baja ley usando la tecnología de Blue Planet Strategies DEMET™ (Dynamic Electrode Mining Effluent Treatment, por sus siglas en inglés), que tiene como objetivo salvar la brecha de procesamiento entre la solución débil de lixiviación en operaciones de extracción por solventes/electrowinning (SX/EW), removiendo electroquímicamente los metales a partir de corrientes débiles y a la vez generando productos concentrados en metales objetivo en un análogo funcional de extracción por solventes (SX). Se estudió el tratamiento de la débil solución de lixiviación pregnant (PLS por sus siglas en inglés) y se usó para estimar los impactos económicos y de producción para una hipotética lixiviación en pilas de cobre brownfield y una operación aumentada DEMET usando SX/EW para tratar el "mineral de desecho." Se presenta la remoción de cobre a un 86% de eficiencia en las placas por debajo de 0,1 g/L de cobre con un consumo de energía de 0.55 kWh/lb de cobre y una concentración del producto mayor a 10 g Cu/L. El modelamiento arrojó aproximadamente $2/ lb para la producción total de cobre y costos de tratamiento menores o iguales a $1/lb con un inmediato aumento del margen bruto de operación del 12% para el brownfield incrementado. Se indicó también un aumento de la vida de la mina con un margen bruto promedio de 38% en la producción aumentada de "mineral de desecho" con valores de cobre de $3.25/lb.

Jan 1, 2014

By C-D. Johansson, B. Ögren, B. M. Ludvigsson, K-Å. Johansson, R. Lindh, G. Berg, M. Maliarik

This paper presents the High Current Density (HCD) Silver Electrorefining Process. A 25-year history of development of the silver electrorefining process as well as associated equipment is given. The process is simple and robust, but at the same time highly automated. With low operating costs and man power requirement it allows consistent production of 99.99 % quality cathode silver. The process ensures that no toxic gases are formed in the working environment. Silver Electrorefining is a heart of a Silver Refinery plant covering the complete range of processes from casting of silver Doré anodes to casting of the bars of refined silver or/and silver granulation. The process has been successfully applied at 11 installations world-wide with plant capacities ranging from 30 to 1500 tpa.

Jan 1, 2014

By L. Chunpongtong

ABSTRACT Oil sands production occurs on a massive scale, making orebody estimation a challenge. In rainy conditions, operators can have difficulty accessing ore at the mapped location. Without enough inventory as a buffer, the high-cost stockpile is depleted quickly, necessitating the removal of significant amounts of overburden and interburden to meet plant feed requirements. The inventory curve—a plot of ore inventory on a period-by-period basis—plays an important role in selecting an appropriate scheduling scenario. This paper presents a programmable method for creating an inventory definition by using a pit optimization tool.

Jan 1, 2014

By O. Rondon

Localized uniform conditioning is a technique developed to spatially locate selective mining unit grades that have been derived using uniform conditioning for the assessment of recoverable resources. The technique has the advantage of producing selective mining unit estimates conforming to the uniform conditioning panel-specific grade-tonnage curve while introducing spatial information at the scale of the selective mining units. This paper describes an alternative technique to localized uniform conditioning which does not explicitly require the uniform conditioning panel-specific grade-tonnage curve to localize the selective mining unit estimates. The technique can therefore be implemented in mining software where uniform conditioning is not available.

Jan 1, 2014

By Imre Gombköto, Zoltán Pap, Ákos Debreczeni, Sándor Nagy

Eddy current separators have become generally used in waste recycling industry during the last decade. There are many papers dealing with separation processes on eddy current separators, and also many article describes particle trajectory and different particle features affecting particle trajectory. These data are used in modeling as well. Within the frame of R&D project called ‚Fundamental research into the exploitation of the economic development potentials of critical raw materials in international co-operation - CriticEl?, authors are aimed for using Eddy Current Separator (ECS) as a mechanical separation step of high value critical elements recovery of selected WEEE’s like display panels, PCB’s. ECS, equipped with 305 mm wide belt, and a concentric magnetic rotor is used for experiments targeted development of methodology for determining separability of different particles on ECS. The subject of our work was to investigate the behavior of model particles with different shape, conductivity (aluminum and copper), orientation and size in order to separate Al and Cu according to the results of many experiments were carried out in this field. However it looks like that throwing distance of one particle is only possible to describe by a certain distribution for even the same particle within the frame of the same conditions. Sample mean and standard deviation are depending on some of the particle feature and acting forces. The paper is going to draft the first results on the relationship between distribution of throwing distance and particle properties.

Jan 1, 2014

By Paul Kunze

When a new bridge was needed across the upper reaches of the Yellowstone River in Montana, removing the old concrete bridge piers became an environmental concern for the highway department engineers. The location is about fifty miles downstream from the north edge of Yellowstone Park. The determination was made by the federal and state agencies charged with protecting the resource, that the old piers had to go but the river bed had to remain unchanged. Concerns were expressed that removing the concrete presented the potential for environmental damage to this protected portion of the river. These concerns prompted the state to place stringent restrictions on the contractor in the way they carried out the demolition and disposal of the piers. The reinforced concrete masses had to be removed to an elevation at least fifteen feet below the river bed and every bit of concrete debris had to be removed from the river channel. Explosive removal was discouraged, but the only other options: saw cutting, mechanical or chemical breaking, were not viable.

Jan 1, 2014

By Joshua Hoffman, Rob Farnfield, Catherine Johnson, Braden Lusk, Morgan Lane

IMESAFR (IME Safety Analysis for Risk) is a quantitative risk assessment software tool developed by the Institute of Makers of Explosives (IME) and A-P-T Research, Inc. It is used for managing risk in the commercial explosives industry, the newest version of the software was completed in 2012. This paper discusses the use of this software package in conjunction with data collected for a television series on the reenactment of the ‘London Blitz’, a 57-day bombing of the City of London in 1940. In this reenactment, purpose built structures using period design and materials were constructed at a test facility in the North of England. Five devices ranging in size from 20 kg (44 lb) to 1100 kg (2400 lb) were detonated at varying distances from the structures; each blast was monitored by EPC-UK and the resulting structural damage was analyzed. Data recorded from the blasts included high-speed videos, photographs before and after each event and air overpressure readings. The same data was inputted into the IMESAFR software package to assess the risk imposed on the residents of London during this time. The appropriateness of this tool for evaluating structures built using historical practices is discussed. Data from the full scale tests is compared to effects predicted by IMESAFR. Further analysis of the risk recommendations produced by IMESAFR is compared to the actual damage assessed during the large scale tests.

Jan 1, 2014

By Jiongtian Liu, Jianjun Wu, Yongzhou Wan, Li Feng

"Mechanical Thermal Expression (MTE) is a developing non-evaporative lignite dewatering technology. It has been shown to effectively dewater high moisture content in low rank coals via the application of mechanical force and thermal energy at elevated temperatures. In this paper, the dewatering behavior of Yunnan Xiaolongtang lignite during the MTE-process was studied. Furthermore, how variations in temperature and pressure during the MTE process affect the surface oxygen functional groups and pore structure were also discussed using Fourier transform infrared spectrometer (FTIR) and mercury intrusion porosimetry (MIP). Increases in MTE temperature and pressure resulted in significant reductions in residual moisture content and moisture holding capacity, along with the increase of fixed carbon content and reductions of other elements content, especially oxygen content, which have been largely attributed to the destruction of the surface oxygen functional groups and porosity in lignite. The optimized technology conditions are temperature 150~220°C and pressure 7~10MPa. The residual moisture content of the lignite treated by MTE under the conditions of 200°C and 10MPa is decreased to 8%, while the dewatering rate exceeds 76 % and the calorific value approaches 22 MJ/kg. The experimental results offer a deeper understanding of the influence of process parameters on the lignite stuctures and properties. The reduction in residual moisture content, surface oxygen functional groups and pore volume under increasingly severe MTE conditions are suggestive of the structure changes that accompany increased coalification (rank) within the lignitic range."

Jan 1, 2014

By G. Voiloshnikov, A. Bogudlova

"The deleterious effect of carbonaceous matter during cyanidation of gold ores (so called preg-robbing) has been recognized for many years. Based on this, a new method using flotation to reduce the content of carbonaceous matter was developed. Low-sulfide gold-bearing ore with carbonaceous matter of 0.14% from a Russian deposit was processed. The purpose of these tests was to compare two flow sheet options. Option I comprised removal of carbonaceous product prior to sulfide flotation. Option II comprised removal of carbonaceous matter from flotation concentrate. It was found that the content of carbonaceous material can be reduced in sulfide gold-bearing concentrate prior to leaching. High gold recovery was observed during the separation of carbonaceous material prior to sulfide flotation using Option I. Due to lower reagent consumption the costs for reagents were decreased using Option II. The results have shown the effectiveness of a new method. Patent No. 2783808 was obtained for removal of carbonaceous material prior to sulfide flotation. This information will be used to design a large processing plant flow sheet in Russia."

Jan 1, 2014

By Richard Hosley, James Daley

Every grey haired member of the explosive’s industry has said at least once, “We have to get some younger blood into our industry, I might want to retire someday.” And many a youngster who loves to see explosions has wondered how to get involved in such an exciting, yet intimidating, industry. While there are many answers to these questions, an internship program is a great answer to both

Jan 1, 2014

By Mike Johnson, Niels Verbaan, David Dreisinger

The Search Minerals Foxtrot project in Labrador represents a significant Canadian resource of rare earth elements rich in the sought after heavy rare earth elements (19.8% HREE/TREE). A preliminary economic assessment of the project indicated that the project is technically feasible and economically attractive. A variety of metallurgical test programs have been undertaken which have led to significant streamlining and simplification of the process flowsheet. The improved flowsheet should allow Search to reach production earlier and will use conventional processing equipment. The results of these test programs are presented and discussed in this paper.

Jan 1, 2014

By Sadettin Bagdatli, Ali Kahriman, Umit Ozer, Alper Celtikci, Yucel Karakus

Due to population growth and rapid urbanization in Turkey, the need for the construction of residential units, transportation and infrastructure facilities has become increasingly more pressing. Since rock units encountered in the surface and underground in the construction of the subway, infrastructure and housing facilities, it is a necessity to use blast excavation methods. In recent years, large housing construction projects have been carried out especially in Turkish metropolitan areas, involving foundation excavations giving rise to great amounts of earthmoving. Since rock units encountered during foundation excavations are usually hard and solid, excavation with conventional machinery proves to be inadequate and unproductive, hence the necessity for the application of blasting technology.

Jan 1, 2014

By J. Daraisme

Société le Nickel (SLN) exploits the Dôme lateritic nickel orebody at its Tiébaghi operations in New Caledonia. The site geology has an obvious bearing on recovery and metallurgical performance, and the controls are extremely complex at all scales: lithology, oxidation-reduction conditions, mineralogy, and multivariate geochemistry. In that context, establishing an adapted recoverable resource estimation method that is efficient and transparent proves an interesting challenge. The method must address the key notions of: ? Support effect: the exploration data-set can only warrant the estimation of large panels 20×20×3 m3, which are much larger than the selective mining units (SMUs) of 5×5×3 m3 ? Information effect: the selection at production stage uses estimates based on information much denser than that available for mine planning. The problem is rendered more complex in this type of deposit by the fact that the additive variables used for any estimation process (metal accumulation and ore tonnage) are not the ones used to establish the selection at mining stage (i.e. the nickel grade of SMUs, which is the ratio of accumulation on tonnage). Eventually, the selection criteria involve not only Ni grades but also other constituents such as Al2O3, Fe2O3, MgO, and SiO2. The solution presented in this paper is the construction of a platform of SMU multivariate simulations in the saprolitic horizon, together with efficient post-processing aimed at producing the multivariate recoverable resource estimates. The efficiency constraints imposed by the number of blocks to be simulated (1.5 million) lead to resorting to direct block simulations. The underlying multivariate discrete Gaussian model (DGM), the validity of which is tested beforehand, is put to good use to mimic the selection process at the mining stage, by offering the ability to simulate in each block a composite value located at random within the block. Finally, the paper presents the application of a scenario reduction algorithm to pick a representative subset of a few simulations to help appraise the risk attached to the downstream phases (reserve optimization, mine sequencing) of the project. The implementation presented here is for the first generation of the Scenario Reduction plugin built in Isatis software, where measuring the distance between the initial set of scenarios and the reduced set is based on Ni quantities only. Research is under way to adapt the measure to the true multivariate nature of the problem.

Jan 1, 2014

By L. M. Lowe, D. G. Feasby, J. R. Goode

"Rare earth resources usually contain minor amounts of radioactive elements. The most widely recognised sources of radioactivity are associated with thorium and uranium. However, also present in the resources are isotopes of rare earth elements (REE) that are themselves radioactive, including lanthanum (La-138), lutetium (Lu-176) and samarium (Sm-147). These radioisotopes, as well as remnants of the natural thorium (Th-232) and uranium (U-238, U-235) decay series, can contribute to significant levels of radioactivity in mixed REE concentrates and in separated products. Levels such as these can present challenges for transport, transboundary movement, product storage, workers’ health and safety, as well as waste management issues at the facilities that separate out the individual REE’s. These are discussed in this paper. A particularly challenging radioactive isotope is Ac-227 (a decay product in the U-235 decay series). Actinium behaves chemically similar to lanthanides and hence normally concentrates with REE multi-element composites. Reliable analysis of Ac-227 is not widely available and the methodology required to deal with this challenge is briefly described. A principle reason for minimization of radioactive content throughout REE processing is restrictive specifications by concentrate purchasers in order to reduce waste management challenges. Approaches to the minimization of radioisotope content in REE concentrates and separated products are outlined in this paper."

Jan 1, 2014

By Patrick Polk

For many years, sulfuric acid producers all over the world have been forced to meet ever more strict environmental regulations to reduce SO2 emissions. The sulfuric acid industry has implemented new solutions in order to comply with the new lower SO2 emissions target. Haldor Topsoe (Topsoe) has responded to this challenge by continuously improving the range of VK sulfuric acid catalysts and providing tailor-made catalyst solutions to meet the demands of the sulfuric acid producers for lower SO2 emissions. Reducing emissions through catalysis: requires less capital than installing a scrubber, requires no additional process chemicals, generates no waste or by-product to dispose of. In 1996 Topsoe introduced VK69, a cesium-promoted vanadium catalyst, designed for operation in the pass(es) after the intermediate absorption tower in double absorption plants. The high activity of VK69 allows for a more than 50% reduction in SO2 emissions from existing double-absorption plants. Topsoe currently has more than 110 installations of VK69. To comply with the still more stringent regulations being placed on the sulfuric acid industry to lower SO2 emissions, Topsoe has developed a new sulfuric acid catalyst designated VK-701 LEAP5™. This catalyst was introduced to the market in 2010. VK-701 LEAP5™ is based on a novel technology which circumvents the internal transport deficiencies of existing commercial sulfuric acid catalysts and thereby offers exceptionally high activity in strong, SO3 rich gases. Sulfuric acid plants have used this catalyst to meet emissions requirements lower than previously believed possible with a catalyst only solution. This paper will present examples on how to reduce emissions by implementing a tailor-made catalyst solution using VK69 and VK-701 LEAP5™.

Jan 1, 2014